Refining hydrocarbon



- Patented Oct 25, 1932 UNITED STATES PATENT OFFICE PAUL ZURCHER, OF PONCA CITY, OKLAHOMA, ASSIGNOR TO CONTINENTAL OIL COMPANY, OF PONCA CITY,OKLAHOMA, A CORPORATION OF DELAWARE BEFINING HYDROCARBON No Drawing.Original applicationfiled August 13, 1928, Serial No. 299,443. Dividedand this application filed October 30, 1929. Serial No. 403,655.

This is a division of my application Serial No. 299,443, filed August13, 1928.

The present invention relates to the preparation and use of specificallyactivated car- 5 bon, and has special reference to the refining ofhydrocarbons to remove impurities such as sulphur, coloring matter,gums, etc. The invention also has special reference to the refining ofhydrocarbons in the vapor phase at,

below, or above atmospheric pressure.

In refining hydrocarbons by passing vapors over or through activatedmaterials, either of an adsorbent nature or of a catalytic nature, it isimportant to minimize decomposition or cracking of the hydrocarbons, andto remove the impurities in an eificient manner with eflicient recoveryof purified hydrocarbons.

The present invention aims to accomplish the foregoin and for thisvpurpose utilizes activatedcarbon as a refining agent. I have found thatthere are a great variety of activated carbons which are specificallydiiferent in action when employed in the process of this invention, andthat none of the commers cially available carbons on the market meet themost exacting requirements of the process. I have also found thatspecially prepared carbons are far more effective and eificient incarrying out the process. I have also found that specially preparedcarbon has specific properties dependent upon the mode of preparation oractivation, and in consequence I am enabled to prepare specific carbonsfor specific conditions that may be encountered in refining. I

Accordingly, the present invention contemplates the preparation ofspecifically activat-- ed carbons, particular uses of the specificallyactivated carbons, and the refining of hydrocarbons by the use ofactivated carbons, particularly for the removal of sulphur, coloringmatter and gums.

Various other objects and advantages of the invention will be apparentfrom the fol lowing detailed description of the process as contained inthe various examples herein after given.

In order best to explain the nature of the invention I will firstdescribe the process of 50 refining, and then the methods of preparingthe activated carbons used in refining, for

- the reason that knowledge of the use to which the carbon is put willmake intelligible the reasons for varying the activation process.

In general, if a hydrocarbon vapor to be refined is passed overactivated carbon maintained at a predetermined temperature which may bebetween approximately 400 C. to ap- 1proximately 600 (3., the sulphurcontent can e greatly reduced, and substantially re- 63 moved, giving asweet decolorized distillate. Under the same conditions, except for alower carbon temperature, color can be completely removed, but theover-all sulphur reduction is less eificient, the first fractions be ingsweet, and the later fractions containing considerable sulphurcompounds. Although sulphur removal is not effected in these laterfractions at the same time color is removed, it has been found that thenature of the sulphur compounds is altered by passage through the carbonso that they can be readily removed by other methods. I have found thatfiltering the condensate through activated carbon, and even a waterwashing is effective to remove these altered sulphur compounds.

Example I .As a particular example of the foregoing the followingdetails of operation are given. Active carbon prepared ac cording to themethod of Example III, given below, is heated to a temperature of 610 C.in a suitable chamber through which vapors may be passed in contact withthe carbon. Crude gasoline, having a sulphur content of 35 0.125%,obtained by topping crude oil from Artesia, New Mexico, is distilledthrough the heated carbon. Distillation through the carbon is soconducted that the time of contact of the vapor with the carbon issufficiently short to avoid cracking the vapors. I have found that thevapors may be passed through the carbon in one-tenth of the time whichwould be required for'cracking. The gumsv and color are removed, andsulphur content is reduced to 0.01% or less.

Example I[.Under the same conditions as in Example I, except as tochanging the temperature from 610 C. to 500 (1, the distillate iscolorless, the first fractions are sweet,

and the later fractions contain increasing amounts of hydrogen sulphide.The sulphur containing fractions may be sweetened by filtering through alayer of activated carbon, or by washing with water.

Consequently, the refining process comprises passage of the hydrocarbonvapors through heated carbon to effect removal or alteration of theimpurities, followed, if necessary, by reduction in quantity or removalof residual impurities. The preferred process is distillation throughcarbon at a temperature which yields a colorless or suitably low-coloredproduct, which may have no sulphur, or which may have an altered sulphurcontent capable of subsequent removal.

One advantage of this process is the permitted regeneration of theactivated carbon in situ. I have found that steam may be passed throughthe carbon until the sulphur is removed, or that air may be employed ina like manner. The character of regeneration in each instance isdifferent. With steam the regeneration may be effected at a temperatureat least 510 C. or higher. At 510 C. the steam is very active whichindicates that even lower temperatures couldbe used. Consequently, I donot consider the stated temperatures as limitations. In using steam inthis manner sulphur is removed both as free sulphur and as hydrogensulphide, and the products may be recovered from the liquid condensate,especially the free sulphur.

Completion of regeneration is determined by failure to secure a positivesulphur test in the condensate with the plumbite solution.

When regenerating the carbon with air a lower temperature is employed,for example 370 C., in order to minimize combustion of the carbon.Sulphur in the carbon is burned to sulphur dioxide. I have found thatactivated carbon prepared from petroleum coke is extremely efficient inremoving sulphur. Yet I find that this is not universally true, sinceits properties in this direction are dependent upon the process ofactivation. This will be clear from the following examples showingmethods of activating the carbon and some of its varying properties.

E trample I I I .100 parts of petroleum coke of 12% volatile content ismixed with 35 parts of fuel oil of from 10 to 20 gravity on the A. P. I.scale. The mixture is then granulated in a suitable machine using verylittle ressure. The grains are fed continuously into a rotary furnace,the hottest zone of which is about 925 C. Steam is fed into the furnaceat the discharge end in" amount to equal twice the weight of the chargebeingintroduced. A furnace passage of about 2 hours is employed. Therecovered product amounts to 40% of the crude mixture, or 54% of thecrude coke. One gram of the product will decolorize about 200 cc of astandard methyl orange solution (1 gram in 5000 cc of water) in 30minutes at C. It has an apparent density of 0.42. It has power to adsorb6% to 7% of its weight of gasoline vapors at a temperatureof meltingice. This carbon may be used for refining hydrocarbons as described inExamples I and II. Hydrocarbon so refined can be made completely freeofsulphur by the process of Example II, filtering the distillate throughan activated carbon. The gum content can be reduced from about 0.6 partsper thousand to about 0.02 parts per thousand. The refined productexposed to direct sunlight for weeks remains with an unchanged color of29, Saybolt.

The foregoing treatment of the carbon to produce the desired capacityfor removing sulphur is in some measure specific as evidenced by thefollowing:

Example [V.Repeating the process of Example III using a longer time ofpassagethrough the furnace, that is, an increase from 2 hours to 3%hours, produces a carbon which will decolorize 350 cc of the standardmethyl orange solution as compared to 200 cc of the two-hour product.The apparent density is 0.41 as compared to 0.42, but the gasolineadsorption power jumps from 6% up to as high as 20%. Its power to act onsulphur compounds in the oils is nil.

Example V.-Another process which activates petroleum coke so that it isefficient for removal of sulphur by my refining process is the same asone described and claimed in my copending application Ser. No. 209,441,filed August 13, 1928.

parts by weight of petroleum coke of 12% volatile content are mixed with20% phosphoric anhydride in the form of ortho or meta-phosphoric acid,and 15% of a heavy hydrocarbon such as a residual oil. The mass isgranulated and *passedthrough a rotary furnace for a period of about 3hours. The hottest zone is at a temperature of about 950 C. to 1000 C.although a variation of temperature is permitted. Steam is admitted atthe discharge endin amount to equal about one-third the carbon chargebeing introduced.

The product runs about 55% of the coke initially charged. One gram ofthe carbon will decolorize 900 cc. of standard methyl orange solution,and will adsorb about 12% gasoline vapor at a temperature of meltingice. It is a very effective refining carbon .fqrthe process of thisinvention.

*Eaizmple VIP-Another process of making suitable refining carbon frompetroleum coke that softens when heated comprises granulating the cokeand treating as in Example III with steam, but under differentconditions. A furnace passage in 4 hours with a maximum furnacetemperature of 900 0., and steam equal to twice the weight of thecharge, produce a yield'of 43%. The product will des colorize not over50 cc. of standard methyl orange solution and will adsorb'but 3% to i 4%of gasoline vapor. .In spite of low efiiciency as indicated by thesetests, it is extremely effective for my refining process. a. It iscapable of removing all the sulphur, and at the same time producing amarketable distillate without any further treatment, eliminating eventhe water wash. When this carbon is used it is maintained at atemperature of 370 C. when the hydrocarbon is distilled through it. It can beregenerated with steam as above described.

In order to show the value of my carbon as employed in my refiningprocess I submit herewith a table showing the comparative tests madewith commercial carbons and with my carbons.

test appear to have no significance in indicating the power to removesulphur. The property is no doubt dependent upon complex relationsinvolving the type and character of the activation process, the type ofraw material employed as a base for the carbon, the conditions ofactivation, the type of Process III.-O'0mparison of different carbonsfor refining purposes aso me me y o Name Ash adsorption orange Gasolinedistillation at 780 F.(300cc.) Remarks decol.

. 1. Grams to an Recov. C 1 Odor D ct r after i 1" x4 tube per cent 0 orwater wash late ,D cent Nathan on 20 mesh... 4.2 7.2(78)- 300 8.8 93.0Strong ya- Cracked Almost sweet 0.024 Much cracklow 0. 0% ing Darco12+20mesh.. 13.7 15.1(7s) 350 17.0 Leaks Lig t 5 8 Sweet Almost ee 3-3;:Sq e crack- OW 111g. Norit A. granulated" 7.9 20.5 (78) 300 9.0 94.0St1rongyel Fair Almost sweet M ueh crackow ing Norit STA -20+50 3.19.0(78) 300 14.0 89.5 Dark yel- Fair Almost sweet 0.023 Much crackmeshlow. 0. 026 mg National Carbon 00. 0.4 15.0 (78) 475 25.8 85.0 Brownyel- Cracked Almost sweet 8. Very kmuch w crac mg Our #52 4.7 11.1 (62)350 25.0 Regen- 97.5 Light 3 31- Sweet Absol. Sweet No cracking erated wOur 551 1.8 9.1(62) 350 22.0Regen 97.3 W a}: e r Sweet Sweet 0.004Nocracking erated white 0. 003

In the above table the carbon designated No. 51 was made by thefollowing process: parts of coke containing 12% volatiles and ground to200 mesh, and 25 parts of fuel oil (15 A. P. 1.), were mixed,granulated, and heated in a furnace for three hours to a maximumtemperature of 925 (3., using 1.9 parts by weight of steam for each partof the crude mixture -charged. Carbon No. 52 was prepared by mixing 100parts of the same coke containing 12% volatiles, 30 parts phosphoricanhydride, and 15 parts of fuel oil and in warfare; for purification ofgases like carbonic acid by a selective retention of impurities from thegas when the absorbed gas is removed from the carbon.

' From the foregoing description and the above table it may be readilycomprehended that I have provided a carbon and a refining process thatare effective and efiicient. It is to be understood that the inventionis not to be limited by the details given in the foregoing examples, andthat various changes may be made in accordance with the scope of theappended claims.

I claim:

1. The method of purifying hydrocarbons which comprises rapidly passingvapors of the hydrocarbon through activated carbon at a temperature inthe vicinity of 400 C. to 600 C. the velocity of the vapors through saidactivated carbon being such that treat-- ment is effected withoutcracking the vapors, and condensing the vapors.

2. The method of purifying hydrocarbons containing sulphur impuritieswhich comprises rapidly passing vapoisof the hydro carbon throughactivated carbon at a temperature in the vicinity of 400 C. to 600 C.the velocity of the vapors through said activated carbon being such thattreatment is effected without cracking the hydrocarbon, condensing thevapors, and removing sulphur compounds from the condensate.

3. The method of purifying hydrocarbons which comprises passing vaporsof the hydrocarbon through activated carbon at a temperature in thevicinity of 400 C. to 600 C. at a velocity such that the hydrocarbonsare exposed to said temperatures for substantially one-tenth of the timeinterval required for cracking, whereby cracking is, avoided, andcondensing the vapors.

' 4. The method of purifying hydrocarbons which comprises passing vaporsof the hydrocarbon through activated carbon at a temperature in thevicinity of 400 C. to 600 C. at a velocity such that the hydrocarbonsare exposed to said temperatures for substantially one-tenth of the timeinterval required for cracking, whereby cracking is avoided, condensingthe vapors, and removing sulphur compounds from the condensate.

PAUL ZURCHER.

